The stomach, appendix, jejunum, ileum, ascending colon, transverse colon, descending colon, liver and spleen are internal organs associated with the gastro intestional tract. Some or all of the structures are totally or partially suspended by mesenteries which also contain blood vessels, lymphatics and lymph nodes. The mesenteries vary in thickness, but all contain fatty tissue and blood vessels which vary in size from 1.0 cm. in diameter down to less than 0.1 mm. in diameter. The greater omentum is a double fold of mesentery and it too carries large numbers of blood vessels of varying size, and the thickness of the greater omentum is quite variable from one patient to another.
There are stapling devices for closing the bronchus, pulmonary artery, pulmonary veins, for closure of the large or small intestine, for closure of the stomach or stapling of the stomach, for end-to-end anastomosis of the intestines, for side-to-side anastomosis of the intestines and for individual ligation and for division of a blood vessel. In addition, there are a variety of occluding clips for blood vessels and skin staplers. Because of the fatty tissue and the variety of sizes of blood vessels present in the mesentery and the omentum, the available staplers are not satisfactory for stapling the mesentery and the omentum. Current appliers ligate only one or a few vessels at a time and commonly tear blood vessels in the vicinity of their use, requiring time consuming repairs after ligation of the intended vessel.
Pruitt, U.S. Pat. No. 4,848,637 and Pruitt, U.S. Pat. No. 4,930,503 describe process, stapler and cartridge suitable for stapling the mesentery and the omentum using three or more rows of staples having different crown size in at least one row of staples as compared to the other row of staples, including an arrangement of staples in which the crown sizes of alternate staples in the same row differ from crown size of the staples between said alternate staples. This arrangement is based on the fact that the staples having larger crowns also have longer prongs (or legs) and the staples having smaller crowns have shorter prongs. This is based on the fact that the prong size is determined by the requirement to reach halfway across the bottom of the crown and also to have enough additional length to form a loop under the crown. This loop serves a similar function as a stitch in a suture or ligation used to seal off the blood vessels after an incision has been made in human tissue. The larger the loop is to be, the greater will the length of the prong be in excess of that required to reach one-half the length of the crown. With mesentery and omentum a combination of large loops and smaller loops is desired to seal off the flow of blood from the blood vessels severed by the incision. Advantageously each blood vessel and also some fatty tissue to squeeze the blood vessel shut is embraced by a loop of the staple.
When the crown sizes are the same in a number of rows of staples, as provided in commercially available cartridges of staples, the staples in one row are staggered with respect to the staples in the adjacent row or rows. The staggering in each case is effected by positioning the beginning end of the first staple in the second row of staples opposite the midpoint of the first staple of the first row of staples. This means that the midpoint of each of the staples in the second row of staples is opposite a gap between staples in the first row. It also means that the gaps between the staples in the second row are opposite the midpoint of adjacent staples in the first row. The midpoint of the staples is where the ends of the prongs on the underside of those staples come near each other and in many cases leave a gap between each other and between the prong ends and the crown. In some cases, the curvature at the end of a closed staple leg is formed such that a space exists between formed legs. These conditions mean that blood vessels which come in the gaps between staples in one row will not be encased in a loop in the adjacent row of staples.
In Pruitt, U.S. Pat. No. 4,941,623, a process, a stapler and a staple cartridge are disclosed suitable for use on the mesentery and on the omentum, the use of which process, stapler and cartridge are capable of effectively stopping the bleeding of blood vessels in that part of the mesentery or of the omentum which is being resected. These are designed to apply three or more rows of staples of the same size "crown" or main body portion of the staples, the rows being substantially parallel to each other and the staples in each row being staggered one-quarter of the crown length with the staples in the adjacent row or rows of staples. There is at least one row in which the prong lengths of the staples differ from the length of the staple prongs in the other row or rows.